Catalina M. Lladó

From UML models to software performance results: an SPE process based on XML interchange formats

The SPE process uses multiple performance assessment tools depending on the state of the software and the amount of performance data available. This paper describes two XML based interchange formats that facilitate using a variety of performance tools in a plug-and-play manner thus enabling the use of the tool best suited to the analysis. The Software Performance Model Interchange Format (S-PMIF) is a common representation that is used to exchange information between (UML-based) software design tools and software performance engineering tools. On the other hand, the performance model interchange format (PMIF 2.0) is a common representation for system performance model data that can be used to move models among system performance modeling tools that use a queueing network model paradigm. This paper first defines an XML based S-PMIF based on an updated SPE meta-model Then it demonstrates the feasibility of using both the S-PMIF and the PMIF 2.0 to automatically translate an architecture description in UML into both a software performance model and a system performance model to study the performance characteristics of the architecture. This required the implementation of some extensions to the XPRIT software in order to export UML models into the S-PMIF and a new function in the SPEED software to import S-PMIF models, which are also described. The SPE process and an experimental proof of concept are presented.

Performance model interchange format (PMIF 2.0): XML definition and implementation

A performance model interchange format (PMIF) provides a mechanism whereby system model information may be transferred among performance modeling tools. The PMIF allows diverse tools to exchange information and requires only that the importing and exporting tools either support the PMIF or provide an interface that reads/writes model specifications from/to a file. This paper presents a new version of the PMIF specification (PMIF 2.0) and its XML implementation. The paper also describes a prototype that was implemented to prove the concept, in which the exporting tool is SPE/spl middot/ED and the importing tool is Qnap, and it discusses the issues in this and the reverse exchange. It shows the validation of the prototype based on the solution of examples that were exported from SPE/spl middot/ED and imported by Qnap. In addition, it proposes some extensions to PMIF 2.0.

Performance Model Interchange Format (PMIF 2): A comprehensive approach to Queueing Network Model interoperability

The Performance Model Interchange Format (PMIF) provides a mechanism for transferring the system model information among performance modeling tools requiring only that the tools either internally support PMIF or provide an interface that reads/writes model specifications from/to a file. This paper presents the latest version of the specification (PMIF 2): a metamodel defining the information requirements and the corresponding XML schema. It defines the semantic properties for a pmif.xml interchange, the prescribed validation order, errors and warnings, and a tool and Web service implementation. Import and export prototypes for two different types of tools prove the concept. Generally available examples are used for repeatability.

Performance evaluation of an enterprise JavaBean server implementation

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Interchange Formats for Performance Models: Experimentation and Ouput

XML-based interchange formats for performance models provide a mechanism whereby performance model information may be transferred among modeling tools. For example, the PMIF allows diverse tools to exchange queueing network model information. Formats have also been defined for the interchange of LQN, UML, Petri Nets, and others. These formats specify the model and a set of parameters for one run. For model studies, however, it is useful to be able to specify multiple runs, or experiments, for the model. This paper presents an XML interchange schema extension for defining a set of model runs and the output desired from them. It has the expressive power to specify iterations, alternations, assignments of values, actions based on model results and more. Examples illustrate how the experiment interchange extension can be used with a wide variety of performance modeling paradigms. A prototype proves the concept.

A general performance model interchange format

A common, XML-based interface between specifications of quantitative system models and programmed solutions is developed and illustrated with several examples. It is based on the PMIF (Performance Model Interchange Format), which allows queueing network models to be specified in XML and solved by calling any appropriate modelling tool, such as Qnap. The definition of PMIF specifications is generalised by considering more abstract collections of interacting nodes, using concepts compatible with the Reversed Compound Agent Theorem (RCAT). The interactions are more general in that they synchronise transitions in a pair of nodes rather than being restricted to describing traffic flows. The generalised nodes are characterised by the interactions in which they participate, together with their rates and reversed rates, which may be implicit. In this way, generalised queueing networks with negative customers and triggers can be incorporated and fixpoint models can also be handled uniformly through the use of symbolic variables.

A unified approach to modelling the performance of concurrent systems

Abstract Quantitative design is crucial to ICT and it is therefore important to integrate performance modelling techniques into support environments that facilitate the correct construction of computer systems. We consider Performance Modelling Interchange Formats (PMIFs), which allow models to be specified in a uniform way and ported to a number of tools that solve them. We focus on extending the class of models describable in a PMIF that can be solved analytically – specifically, yielding a product-form solution for their equilibrium state probabilities. We use an extension of an established theorem, called the ‘reversed compound agent theorem’ (RCAT) as the basis of the analytical modelling tool into which the extended PMIF feeds models. We describe the RCAT methodology in practical terms, how it is integrated into an extended PMIF, and illustrate our methodology with three examples.

Model Interchange Format Specifications for Experiments, Output and Results

XML-based interchange formats for performance models provide a mechanism whereby performance model information may be transferred among modeling tools. Formats have been defined for the interchange of queueing network models (QNM), layered queueing networks, UML, Petri nets (PNs) and others. These formats specify the model and a set of parameters for one run. For model studies, however, it is useful to be able to specify multiple runs, or experiments, for the model; to collect model output; and to present it in a useful, readable format for analysis and presentation. This paper presents a performance model interoperability framework that brings together performance model interchange formats and experiment specifications with the automatic generation of performance analysis results for presentation and publication. We present the output specifications, the requirements for the types of results to be supported, the issues in the output-to-results transformation, the results specifications and several prototype implementations that demonstrate the viability of the approach. We apply the approach to two distinct modeling paradigms: QNM and PN models. Several proof of concept experiments demonstrate the framework.

Performance Model Interchange Format: Semantic Validation

A Performance Model Interchange Format (PMIF) provides a mechanism whereby system model information may be transferred among queueing network model (QNM) based modeling tools. The PMIF allows diverse tools to exchange information and requires only that those tools provide importing/exporting mechanisms from/to the PMIF. The XML specification of the PMIF allows implementers to use widely available tools to parse the XML file, check the syntax, and simplify the translation to/from the XML format. Those tools, however, do not know the semantics of a QNM so they cannot check the XML to ensure that it contains a valid QNM. This paper presents the study of the validations needed to carry out such a semantic analysis, and the development of a semantic validation tool that can be used by any developer who wants to implement PMIF import/export mechanisms.

A web service for solving queuing network models using PMIF

A performance model interchange format (PMIF) is a common representation for queuing network model data that can be used to move models among modeling tools. This paper demonstrates how Web services can be used to facilitate the use of modeling tools that can interface with the PMIF. The paper describes the design and implementation of a PMIF Web service for the modeling tool Qnap. Additionally, it shows experimental results that prove the viability of such a Web service.